Diesel exhaust aerosols(DEAs) can absorb and accumulate toxic metal particulates and bacteria suspended in the atmospheric environment, which impact human health and the environment.The use of acoustic standing wave...Diesel exhaust aerosols(DEAs) can absorb and accumulate toxic metal particulates and bacteria suspended in the atmospheric environment, which impact human health and the environment.The use of acoustic standing waves(ASWs) to aggregate DEA is currently considered to be an efficient particle removal method; however, study of the effect of different temperatures on the acoustic aggregation process is scarce. To explore the method and technology to regulate and optimize the aerosol aggregation process through temperature tuning, an acoustic apparatus integrated with a temperature regulation function was constructed. Using this apparatus, the effect of different characteristic temperatures(CTs) on the aerosol aggregation process was investigated experimentally in the ASW environment. Under constant conditions of acoustic frequency 1.286 kHz, voltage amplitude 17 V and input electric power 16.7 W, the study concentrated on temperature effects on the aggregation process in the CT range of 58–72℃. The DEA opacity was used. The results demonstrate that the aggregation process is quite sensitive to the CT, and that the optimal DEA aggregation can be achieved at 66℃. The aggregated particles of 68.17 μm are composed of small nanoparticles of 13.34–62.15 nm. At CTs higher and lower than 66℃, the apparatus in non-resonance mode reduces the DEA aggregation level. For other instruments, the method for obtaining the optimum temperature for acoustic agglomeration is universal. This preliminary demonstration shows that the use of acoustic technology to regulate the aerosol aggregation process through tuning the operating temperature is feasible and convenient.展开更多
The visualization and analysis of a novel acoustic-particulate system is the objective of this study. The system is composed of rice-husk fired smoke particulates (36.7 nm-840 μm) and one annular resonant circular-tu...The visualization and analysis of a novel acoustic-particulate system is the objective of this study. The system is composed of rice-husk fired smoke particulates (36.7 nm-840 μm) and one annular resonant circular-tube waveguide contrarily coupled with two sound sources. The collective interaction behavior process of smoke particulates in an inhomogeneous acoustic field is displayed during an experiment and a simulation. The result shows that the aggregation and fragmentation of particles under a change in resonant frequencies and sound pressure amplitude is extremely complex. This complex process consists of dynamically tuning the particle characteristics to attain stripes shaped like thin-films/umbrellas and clusters with volume-change/fragmentation. The balanced modulation of the acoustic radiation force and secondary radiation force to alter the particle characteristics (size and stack density) is verified to be the control mechanism of the particle system. The intermediate variable of the process control is the acoustic contrast factor (Φ) related to the physical characteristics of the growing particulates. The value plus-minus alternation of Φ results in different particulate processes. This study can enhance the application of aerodynamic acoustic-particulate-fluid systems for environment protection, energy fuel conversion, and industrial production.展开更多
基金supported by the National Nature Science Foundation of China (No. 11190015)the Scientific Research Foundation of Graduate School of Southeast University (No. YBJJ1547)+1 种基金the Research Innovation Program for College Graduates of Jiangsu Province (No. KYLX15_0069)the Fundamental Research Funds for the Central Universities (Nos. 3203007706, 3203007206, 3203005101, 3203006701, 3203006711)
文摘Diesel exhaust aerosols(DEAs) can absorb and accumulate toxic metal particulates and bacteria suspended in the atmospheric environment, which impact human health and the environment.The use of acoustic standing waves(ASWs) to aggregate DEA is currently considered to be an efficient particle removal method; however, study of the effect of different temperatures on the acoustic aggregation process is scarce. To explore the method and technology to regulate and optimize the aerosol aggregation process through temperature tuning, an acoustic apparatus integrated with a temperature regulation function was constructed. Using this apparatus, the effect of different characteristic temperatures(CTs) on the aerosol aggregation process was investigated experimentally in the ASW environment. Under constant conditions of acoustic frequency 1.286 kHz, voltage amplitude 17 V and input electric power 16.7 W, the study concentrated on temperature effects on the aggregation process in the CT range of 58–72℃. The DEA opacity was used. The results demonstrate that the aggregation process is quite sensitive to the CT, and that the optimal DEA aggregation can be achieved at 66℃. The aggregated particles of 68.17 μm are composed of small nanoparticles of 13.34–62.15 nm. At CTs higher and lower than 66℃, the apparatus in non-resonance mode reduces the DEA aggregation level. For other instruments, the method for obtaining the optimum temperature for acoustic agglomeration is universal. This preliminary demonstration shows that the use of acoustic technology to regulate the aerosol aggregation process through tuning the operating temperature is feasible and convenient.
基金This paper was supported by the Natural Science Foundationof Jjiangsu Province of China(Grant No.BK20191019)the Natural Science Research Project in Colleges and Universities in Jiangsu Province of China(Grant No.19KJB470022)+1 种基金the Scientific Research Startup Foundation funding of High-level Introduction Talents of Nanjing Institute of Technology(Grant No.YKJ201912)the Open Fund Project of the Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education of Southeast University.
文摘The visualization and analysis of a novel acoustic-particulate system is the objective of this study. The system is composed of rice-husk fired smoke particulates (36.7 nm-840 μm) and one annular resonant circular-tube waveguide contrarily coupled with two sound sources. The collective interaction behavior process of smoke particulates in an inhomogeneous acoustic field is displayed during an experiment and a simulation. The result shows that the aggregation and fragmentation of particles under a change in resonant frequencies and sound pressure amplitude is extremely complex. This complex process consists of dynamically tuning the particle characteristics to attain stripes shaped like thin-films/umbrellas and clusters with volume-change/fragmentation. The balanced modulation of the acoustic radiation force and secondary radiation force to alter the particle characteristics (size and stack density) is verified to be the control mechanism of the particle system. The intermediate variable of the process control is the acoustic contrast factor (Φ) related to the physical characteristics of the growing particulates. The value plus-minus alternation of Φ results in different particulate processes. This study can enhance the application of aerodynamic acoustic-particulate-fluid systems for environment protection, energy fuel conversion, and industrial production.